In many on-highway and off-highway operations, an operator must remain seated for extended periods of time while controlling operation of a machine. Seats, therefore, are typically designed to permit the operator to perform tasks from a comfortable position and isolate the operator, as much as possible, from vibrations of the machine. This may be particularly important for machines operating over a rugged terrain that may cause extreme vibrations of the machine. Such vibrations, as should be appreciated, may interfere with operator control and may cause the operator to fatigue more quickly.
As a result, a variety of seat suspensions have been designed to absorb and/or dissipate the forces imparted to the seat. Various means have also been adopted to permit adjustment of the height of the seat to accommodate operators of various sizes. Such adjustment means is generally arranged to operate within the base area below the seat and is typically mechanically and/or electronically actuated. In many arrangements, regardless of the type of suspension system employed, the height adjustment means is often coupled with the seat suspension.
For example, many passive suspension systems utilize an air spring, in conjunction with other devices, for both seat suspension and height adjustment. Although both functions may be adequately performed, it should be appreciated that, by coupling the seat suspension and the height adjustment, a certain level of dependence is placed thereon. Specifically, adjusting the seat height by increasing or decreasing the amount of pressurized air within the air spring may undesirably alter the suspension. Therefore, it may be desirable to separate the suspension and height adjustment functions provided for the seat.
U.S. Publication No. 2007/0284927 teaches a suspension for a seat that is independent of height adjustment. Specifically, separate air bags are provided for suspension and height adjustment. In an effort to provide a more compact base for the seat, the height adjustment air bag is configured to receive the suspension air bag within a central portion thereof. In addition, the height adjustment air bag, being telescopically adjusted around an empty metallic cylinder, is configured to fold itself completely within its allocated height in order to allow for a relatively low minimum seat height. It should be appreciated, however, that there is a continuing need for versatile suspensions that are simply constructed and inexpensive, while still providing the necessary absorption of vibrations and desired range of height adjustment.
The present disclosure is directed to one or more of the problems set forth above.